Weight and mass Flashcards
What is weight?
The force that a body experiences due to its mass, and the size of the gravitational field that it is in.
Is weight vector or scalar, and what is it measured in?
vector, newtons (N)
Which direction does the weight of a body act in on the Earth’s surface?
Inwards, towards the Earth’s centre.
What is mass?
A measure of the amount of matter that is contained within a three-dimensional space.
Is mass vector or scalar, and what is it measured in?
scalar, kilograms (kg)
Is the mass of a body affected by the size of the gravitational field that it is in?
No.
How do you find the weight of an object?
weight (N) = mass (kg) × gravitational field strength (N/kg)
W = m × g
What does the gravitational field strength of a body depend on?
the mass of the body
the radius of the body
(e.g if a body has a large mass and small radius, it will have a large gravitational field strength)
The units are N/kg (newtons per kilogram), but it can also be given as m/s².
What is the gravitational field strength on Earth?
10 N/kg
How is weight measured?
Using a newtonmeter.
What are the units for gravitational field strength?
N/kg
An astronaut has a mass of 58 kg on Earth.
State the astronaut’s mass and weight:
a) On the surface of the Moon (g = 1.6 N/kg)
b) On the surface of Jupiter (g = 26 N/kg)
a) Mass does not change, so 58 kg.
weight = 58 kg × 1.6 N/kg = 92.8 N
b) Mass does not change, so 58 kg.
weight = 58 kg × 26 N/kg = 1508 N
Calculate the value for g on the surface of a planet where a mass of 18 kg experiences a weight of 54 N.
g = W ÷ m
54 N ÷ 18 kg = 3 N/kg
The value of g on Earth is 10 N/kg. On Planet X, the value of g is 25 N/kg. Explain what the mass and weight of a 5 kg brick will be on the surface of Planet X.
W = m × g
Mass isn’t affected by gravitational field strength, so 5 kg.
5 kg × 25 N/kg = 125 N
The weight is 125 N.
What is the equation for weight?
weight (N) = mass (kg) × gravitational field strength (N/kg)
W = m × g
